As set forth in the NRC report of the National Academy of Science entitled "Products from Jojoba" (1975) and subsequent publications by Miwa et al, of the Northern Regional Research Center USDA and Wisniak of Ben Gurion University as reported in Jojoba Happenings published by The Office of Arid Land Studies, The University of Arizona, jojoba oil is a unique oil and a potential replacement for the sperm whale oil formerly obtained from a disappearing and endangered whale species.
Jojoba nut oil differs from most other animal and vegetable oils in that it is not a fat but a liquid wax. Fats, including the seed oils of most other plants, are triglycerides (a mole of glycerol esterified with three moles of long-chain fatty acids). Jojoba and sperm oil are wax esters (one mole of a long-chain alcohol esterfied with one mole of a long-chain fatty acid). Jojoba oil is unique among vegetable oils, as sperm oil is unique among animal oils. Such a vegetable oil has never before been available to industry in commercially usable quantities.
The following characteristics make jojoba oil valuable: its natural purity and molecular simplicity and its stability; it is a non-drying oil, having high resistance to oxidation; it can be stored for years without becoming rancid; its lubricity; its unsaturation (double bonds).
The clear, unsaturated oil can be obtained by pressing or solvent-extraction methods used commercially to isolate vegetable oils from cotton seeds, soybeans, copra and corn.
Such jojoba oil extracts usually have the same wax-ester composition. The acids and alcohols that make up these esters do not vary appreciably with location, soil type, rainfall, or altitude. Moreover, the oil does not change in composition during storage.
Jojoba oil is composed almost entirely of esters of high molecular weight C.sub.18-24, straight-chain monoethylenic acids and monoethylenic alcohols, for example, erucyl 11-cis-eicosenoate of the formula: EQU CH.sub.3 --(CH.sub.2).sbsb.7 --CH.dbd.CH--(CH.sub.2).sbsb.12--O--CO(CH.sub.2).sbsb.9--CH.dbd.CH--(CH.su b.2).sbsb.7--CH.sub.3
These unsaturated acids are a mixture of cis-11-eicosenoic (C.sub.20) and cis-13-docosenoic (C.sub.22) erucic, with small quantities of oleic (C.sub.18) and nervonic (C.sub.24) acids. The unsaturated alcohols are a mixture of cis-11-eicosenol, cis-13-docosenol and cis-15 tetracosenol, with small quantities of alcohols of lower molecular weight. Note that all the alcohols and acids are primarily of the cis configuration.
The conventional position for a double bond in other natural fats or oils composed of C.sub.18 acids is .DELTA.9 i.e. between carbon 9 and 10 of each of the fatty acids, but jojoba oil has mainly .DELTA.11 and .DELTA.13 unsaturation in the alcohols and acids, because of the large amount of C.sub.20 and C.sub.22 chains. All of the jojoba monoenes can be placed in the .omega.-9 acids or .omega.9 alcohols homologous series.
Jojoba oil is chemically more pure than most natural substances; 97 percent or greater liquid wax esters by gas chromatography. Yellow pigments in the oil can be removed with bleaching earths. The oil also has narrow range of wax-ester structures--over 83 percent C.sub.20 and C.sub.22 acids and alcohols.
Cis-to-trans-isomerization of the double bonds has been induced with selenium and nitrous oxide catalysts, producing up to 80 percent trans and 20 percent cis double bonds. The product is a soft solid with a melting point of about 44.degree. C. The amount of such isomers formed can be controlled during these isomerizations by reaction time to obtain any melting point between that of the pure oil (7.degree. C.) and 44.degree. C. A product with a melting point close to that of the human body is desirable. However, both selenium and nitrous oxide previously used as catalysts present potential dermatological problems.
It is an object of this invention to provide a method for the cis-trans isomerization of jojoba oil to provide isomerates of jojoba oil having softening points in the range 25.degree.-40.degree. C.
It is a further object to provide such isomerates by a process whereby the products directly are of sufficient purity for topical application.
Another object is to provide jojoba isomerates having a softening point at about or just below body temperature for use in formulations for topical application to the skin and at other temperatures for other uses.
A further object is to provide isomerates suitable for leather treatment whereby the isomerate of jojoba oil may be incorporated into the hide or skin substrate at elevated temperatures in the liquid form but will revert to semi-solid form in the substrate upon cooling to normal use temperatures (below 35.degree. C.).
These and other objects will be readily apparent from the description of the process and the products derived therefrom which follows.